Epidemiology

Seizures are a common complaint of patients seeking care in emergency departments (EDs). By some estimates, seizures account for 1% to 2% of all ED visits.^1,2 Epilepsy, a condition resulting in recurrent, unprovoked seizures, affects upward of 4 million people; however, as much as 10% of the population will have at least one seizure during their lifetime.^3,4

The natural history of untreated epilepsy is essentially unknown. Based on retrospective data, it was found that 32% of patients with a first epileptic seizure will experience a second attack within 1 month, 51% within 3 months, and 87% within the first year. Some strong predictors for recurrence of seizures include a history of previous neurologic insult, abnormal findings on neurologic examination, or an electroencephalogram (EEG) with epileptiform abnormalities and circadian timing. Approximately 50% patients in whom epilepsy is diagnosed will become seizure free with only single-drug treatment. The addition of a second or third drug will control another 20%, and intractable seizures that are poorly responsive to standard medical treatment will develop in about 30%.

Pathophysiology

Seizures are the result of inappropriate electrical activity in the brain, whereas syncope is caused primarily by transient hypoperfusion within the brain. Uncontrollable electrical discharges can originate from a single area as a result of an underlying structural condition (e.g., tumor, scar, bleeding), or it can be caused by an imbalance in inhibitory (γ-aminobutyric acid [GABA]) and excitatory (N-methyl-D-aspartate) receptor activities. The latter is usually due to toxic or metabolic causes.

The specific seizure activity is determined by the area in the brain involved (Box 99.1). Some of these abnormal electrical discharges may remain localized, whereas others may involve larger areas of the brain. Subsequently, the resultant clinical spectrum includes isolated focal motor activity, as well as generalized motor and sensory abnormalities, including altered mental status and behavioral changes.

Presenting Signs and Symptoms

If available, the previous medical history may reveal risk factors (Box 99.2) associated with the development of seizures. The history can be obtained from the patient (after normalization of mental status), family, primary care physicians, old medical records, or emergency medical service (EMS) personnel.

Differential Diagnosis and Medical Decision Making

The most common serious condition that can be misinterpreted as a seizure is syncope.⁵ There may be important clinical signs or preceding events that can help differentiate these two entities (Table 99.1). In many circumstances patients will be unable to provide critical information, so it is important to try to obtain an accurate description from anyone who witnessed the event (e.g., family, coworkers, EMS personnel). Aside from syncope, several other medical conditions need to be included in the differential diagnosis of seizures (Boxes 99.3 and 99-4; Table 99.2).

Table 99.1 Seizure Disorder versus Syncope

Table 99.2 Seizure Work-up

AIDS, Acquired immunodeficiency syndrome; CNS, central nervous system; HIV, human immunodeficiency virus.

Though rare, various disturbances in electrolytes may precipitate seizures, including hyponatremia, uremia, and hypocalcemia. A serum electrolyte assay is recommended for patients with new-onset seizures. Between 2.4% and 8% of patients with seizures will have electrolyte abnormalities. Despite the fact that the majority of these abnormalities will be clinically insignificant, they should be evaluated and can often be easily corrected in the ED.

If an overdose is suspected, both blood and urine toxicologic screens should be performed.

Measuring the serum prolactin level has no clinical utility in the ED because the results cannot be obtained in a timely manner. However, it may be useful for the consulting service that will conduct further work-up to help differentiate between epileptic (generalized tonic-clonic or complex partial seizures) and psychogenic nonepileptic seizures. It should be performed within 10 to 20 minutes after a suspected event. Prolactin levels of at least twice baseline are considered abnormal (positive). Prudent clinicians may decide to have prolactin levels measured, especially in patients with the symptoms suggestive of nonepileptic or psychogenic seizures.⁶